And the brass knuckles came on. America's frontline agents in the war on terror have hacked into foreign banks, used secret prisons overseas, and spent over $20 million bankrolling friendly Muslim intelligence services. They have assassinated al Qaeda leaders, spirited prisoners to nations with brutal human-rights records, and amassed files equal to a thousand encyclopedias.

But the war is far from over. Last week, Osama bin Laden's top deputy exhorted the faithful to strike at western embassies and businesses. The injunction, from Ayman al-Zawahiri, came on the heels of bombings in Morocco and Saudi Arabia and caused the United States to close diplomatic posts overseas and increase the homeland security warning level from yellow to orange. Al Qaeda, one FBI veteran explained, "has one more 9/11 in them."

With all the headlines about the latest attacks and warnings, however, it is easy to miss the amount of damage America's terrorist hunters have inflicted on bin Laden's ragtag army. U.S. News has retraced the war on terror, starting in the very first weeks after 9/11, to examine in detail how Washington and its allies launched an unprecedented drive, led by the Central Intelligence Agency, to disrupt and destroy bin Laden's operation. Interviews were conducted with over three dozen past and current counterterrorism officials in a half-dozen countries; the magazine also reviewed thousands of pages of court records and analytical reports.

The story--part detective yarn, part spy tale--is one of unsung heroes. It is a story of nameless CIA analysts who matched tortured renditions of Arabic names with cellphone numbers around the globe, of Pakistani soldiers killed while smashing down doors of al Qaeda, of Jordanian interrogators who wore down some of bin Laden's craftiest killers. Much of this has not been told before. A windfall of intelligence has led to a newer, more profound understanding of bin Laden's secret network, intelligence officials say. They have built up dossiers on his followers from a scant few hundred before 9/11 to over 3,000 today. They have identified the core group's sworn membership, now thought to number only 180 true believers. And bin Laden's personal fortune, investigators say, is all but gone.

There's more. The investigators have unearthed a secret history of al Qaeda, discovering documents in bin Laden's own hand, along with records identifying donors to the terrorist group. They have forced captured operatives to help target their comrades--even listening in as a terrorist made a phone call that led to the assassination of a top al Qaeda leader.

On the run. Al Qaeda's wounds run deep. Over half of its key operational leaders are out of action, officials tell U.S. News. Its top leaders are increasingly isolated and on the run. Al Qaeda's Afghan sanctuary is largely gone. Its military commander is dead. Its chief of operations sits in prison, as do some 3,000 associates around the world. In the field, every attempt at communication now puts operatives at risk. The organization's once bountiful finances, meanwhile, have become precarious. One recent intercept revealed a terrorist pleading for $80, sources say.

If the global war on terror has a nerve center, it is the CIA's Counterterrorism Center. At first glance, the CTC looks unremarkable, packed with the cubicles, gray desks, and desktop PCs that make up just about any government office in Washington. A hint that its work might be somewhat out of the ordinary is offered by signposts that mark the corridors. One well-trodden intersection lies at the crossroads of Bin Laden Lane and Saddam Street.

The 9/11 attacks severely shook the CTC--staffed, at the time, by some 600 case officers, analysts, and support personnel. "There was real shock," remembers one official. "Our sole job was to stop things like this." Cofer Black had taken the top CTC job two years before 9/11. A near-legendary figure around the CIA, he had spent 26 years in the agency's covert operations division. But as he stared at the expressions on his staff's faces, he was struck by a look he'd seen only overseas. They reminded him of peering into the eyes of Israeli intelligence officials--how haunted and driven they were. "You appreciate the gravity of your situation when your own people are in the kill box," he says. Black knew al Qaeda well. He had chased Osama bin Laden ever since the Saudi exile tried to kill him in Sudan a decade earlier. Black had returned the favor, drafting CIA plans to assassinate bin Laden long before 9/11--plans that, on the order of higher-ups, sat on the shelf.

All that changed after 9/11. Within days, Black's team came up with its answer to al Qaeda. They called it the Worldwide Attack Matrix. It was an operational war plan, a no-holds-barred leap back to the agency's heyday of covert action. As detailed in Bob Woodward's book Bush at War, the Matrix called for a worldwide campaign to root out its cells in 80 countries. Intelligence officials confirmed to U.S. News the dramatic scope of the Matrix and related proposals. The new plans authorized the use of deadly force, break-ins, and psychological warfare. They allowed the CIA to pour millions of dollars into friendly Arab intelligence services and permitted the once gun-shy agency to work with any government--no matter how unsavory--as long as it got results. On September 17, six days after the attack, President Bush signed an executive order approving virtually everything the CIA had asked for.

Job 1 was destroying the terrorists' Afghan sanctuary. "Nothing emboldened al Qaeda more than us not going after them," says Michael Rolince, who ran the FBI's international terrorism section during 9/11. "I sat through hundreds of meetings at which DOD [the Department of Defense] just listened. The people who fought wars had no role in the war on terror." That was about to change.

"Like the Nazis." The war in Afghanistan caught al Qaeda's leaders off guard. Bin Laden's top people were convinced the United States would respond to 9/11 with merely a volley of cruise missiles, interrogations later showed. By late 2001, the U.S.-led assault had taken out al Qaeda's camps and headquarters, killed hundreds of its followers, and driven the Taliban from power. So rapid was the advance that bin Laden's operatives left behind a motherlode of intelligence--address books, videos, computers, and more. Nearly 100 places yielded valuable intelligence, from caves to training centers. Among the key finds: rosters of trainees at al Qaeda facilities, which gave the CIA a handle on the tens of thousands of jihadists who had passed through some 50 camps across Afghanistan." They were like the Nazis," says an FBI terror expert. "They were meticulous record keepers."

One of the richest finds came in November, after a CIA Predator--a remote-controlled drone-tracked dozens of the enemy to a hotel outside Kabul. A U.S. airstrike blew the building apart, killing close to 100, including Mohammed Atef, al Qaeda's longtime military commander and a key planner of the 9/11 and U.S. Embassy attacks in Africa. Investigators also found in the rubble scores of documents and videotapes that would spark alerts in a half-dozen countries. The videos featured five would-be martyrs railing against "infidels" and vowing to die in suicide attacks. Analysts soon recognized one of them: 30-year-old Ramzi Binalshibh, a glib young Yemeni whose hopes to join the 9/11 hijackers were thwarted by visa problems. Binalshibh was nabbed in Pakistan months later. But another--Khaled Jehani--surfaced only last month in Saudi Arabia, blamed as the mastermind of the suicide car bombings in Riyadh.

From the rubble came another video, one revealing assassination plots against leaders at an upcoming Persian Gulf summit. U.S. officials pulled faces off the tape of some 45 al Qaeda operatives. Also in the ruins: a German passport in the name of one Mohammed Haydar Zammar, a fugitive thought to have recruited the Hamburg, Germany, cell members behind 9/11. Investigators soon caught up to Zammar in Morocco. But perhaps the biggest find was yet another video--a homemade, 20-minute surveillance tape of Singapore. The tape helped officials there thwart an extraordinary series of plots by Jamaat Islamiya--al Qaeda's key ally in Southeast Asia. The militants hoped to spark a holy war by bombing U.S. military sites and businesses, diplomatic posts, and the city's subway and water supply.

The intelligence "take" from the Kabul hotel and other sites was quickly crated up and shipped to the CTC for a closer look. Once considered a backwater at the CIA, the CTC now stood at the heart of the biggest surge of covert action since the Cold War. Cofer Black found himself overseeing secret operations, paramilitary units, propaganda efforts, and more. In the weeks after 9/11, the CTC nearly doubled in size to over 1,100 people, including FBI agents, military officers, and CIA operatives. Before 9/11, the CTC had focused on a dozen different terrorist groups; it now restructured to zero in almost exclusively on al Qaeda. New teams concentrated on finances, leadership, collection of intelligence, and work with foreign governments. Analysts sorted through reams of field reports, satellite photos, and electronic intercepts. Link-analysis printouts, some as big as bedsheets, lined the walls of cubicles, as researchers charted al Qaeda's far-flung contacts. "There are subnetworks of subnetworks," says a top intelligence official. "Thank God we've got giant printers."

By late November, the amount of intelligence pouring in was overwhelming, and CTC staffers understood why. For years, their efforts at fighting terror had vied with a dozen other priorities of U.S. foreign policy. But the message from Washington now was clear. "No nation can be neutral in this conflict," declared President Bush. "You're either with us or you're against us." The results were immediate. "Before 9/11, the cooperation was halfhearted," recalls Richard Clarke, the top counterterrorism official at the National Security Council at the time of the attack. "But now everyone knew the president had a blank check to do whatever he wanted." From the Indian government came intercepts of al Qaeda-tied militants in Kashmir; from Italy, wiretapped conversations of Islamic radicals in Milan; from Sudan, long-awaited files on bin Laden operatives once headquartered in Khartoum. Much to the delight of old pros at the CIA, intelligence arrived even from old foes, among them Libya and Syria.

Bits and pieces. Each day, the CTC took in some 2,500 cables from CIA stations overseas; each week, some 17,000 new bits of intelligence arrived. And that didn't count the huge hauls from Afghanistan. One veteran case officer said the amounts were measured "literally in terabytes"--a terabyte is roughly equal to a thousand bound editions of the Encyclopedia Britannica. The CTC had become the world's single largest collector and coordinator for intelligence on terrorism. So large is the volume of material collected, sources tell U.S. News, that even today, substantial amounts remain unexamined.

By March 2002, the intelligence windfall revealed how little U.S. intelligence had understood about al Qaeda. "There were tremendous gaps in our understanding of al Qaeda's structure, its chain of command, its operational network," says Roger Cressey, director for transnational threats at the National Security Council at the time of 9/11. "Think of it as a 1,000-piece jigsaw in which we had maybe 200 pieces. After 9/11, the pieces came fast and furious."

America's best analysts were troubled as they surveyed the new intelligence. "It was even worse than we thought," says Black, who was struck by Afghan reports of dead al Qaeda fighters with blond hair and blue eyes--Chechens--as well as Uzbeks, Indonesians, and Chinese. "They had internationalized themselves to a far greater degree," he says, "and it was all networked really well."

The body kills, the seized computers and correspondence, combined with prisoner interrogations and other intelligence, offered a fairly complete portrait of bin Laden's secretive organization. Analysts began to grasp how al Qaeda actually operated, from its finances to its key personnel. Before 9/11, U.S. intelligence had files on only a few hundred al Qaeda-trained Islamists. But by March, the number had ballooned to 3,000 and was growing daily.

As their knowledge increased, analysts learned to differentiate among the varied bands of jihadists. As one counterterrorism veteran explained, there are, in effect, two al Qaedas: One is al Qaeda the ideology, which fuels a sprawling network of radical Islamists who draw inspiration from bin Laden but are not his direct disciples. Within that network are what analysts have called al Qaeda's franchises--allied radical groups from Uzbekistan to Indonesia who share bin Laden's dream of a pan-Islamist world. But there is also al Qaeda the organization--a finite, disciplined, Mafia-like grouping with its own rules, finances, and "made" members. Although tens of thousands went through its training camps, very few in fact joined the group. "Al Qaeda is an elite organization that takes very few members," explains Rohan Gunaratna, author of Inside al Qaeda. U.S. intelligence soon concluded that only some 180 followers had sworn bayat, or allegiance, to bin Laden.

The group was also more hierarchical than the CIA had believed. Bin Laden, once thought to be a figurehead, turned out to be a hands-on leader who approved al Qaeda's most ambitious attacks, including 9/11. Descriptions of the group's inner workings, with its religious dogma and blind obedience, appeared almost cultlike, with bin Laden cast as guru. As one top official put it, bin Laden seemed "more Koresh than Napoleon"--a reference to Branch Davidian cultist David Koresh, who perished with his followers in a fiery death in Waco, Texas.

Al Qaeda's finances came into sharper focus, too. Estimates of bin Laden's wealth after 9/11--cited as high as $300 million--turned out to be wildly exaggerated. The Saudi heir had squandered his fortune years before. Al Qaeda's finances were, instead, built on a foundation of charities, mosques, fund-raisers, and businesses that had financed the jihad movement since its formative war against the Soviets in Afghanistan. CIA officers were joined by Treasury and FBI agents in tracing how al Qaeda moved its money--through international banks, hawala underground bankers, and the purchase of commodities like gold and gemstones.

For years, U.S. officials suspected al Qaeda's key support moved through a network of Islamic charities, most of them based in Saudi Arabia and tied to influential Saudis. The evidence of this was now damning. The CIA's interrogations of al Qaeda's top man in Southeast Asia revealed how the group used funds from the Saudi-based al Haramain Islamic Foundation. The Afghan offices of another Saudi outfit, al Wafa Humanitarian Organization, allegedly functioned as an al Qaeda subsidiary--until it was bombed by U.S. warplanes.

Even after 9/11, the Saudis proved less than cooperative. Frustrated, the CIA took matters into its own hands, hacking into Middle Eastern bank accounts to chart the flow of funds to al Qaeda operatives, intelligence sources tell U.S. News. Other times, case officers offered bribes and came away with bank statements and account numbers. By early March last year, U.S. officials had frozen the assets of a half-dozen foundations and urged other nations to do the same. On March 19, Bosnian authorities raided eight locations tied to the Benevolence International Foundation, a multimillion-dollar Islamic fund with offices in nine countries. Inside, officials found weapons and explosives, pilfered government documents on terrorism, plus videos and literature calling for holy war and martyrdom. But the real surprise lay within a sole computer at the foundation's Sarajevo office.

It was a file directory like that on any other PC, except this one was marked Tareekh Osama, Arabic for "Osama's History." As they peered inside, investigators were stunned. The contents were no less than al Qaeda's founding documents: scanned letters, records of meetings, photographs, and more--some of it in bin Laden's own handwriting.

The files laid bare al Qaeda's history in its own words--how it grew from a network backing anti-Soviet fighters in Afghanistan in the late 1980s into a global crusade against infidels everywhere. There was correspondence about moving weapons, money, and people; an organizational chart; and documents on the group's involvement in the Bosnian and Sudan civil wars in the early 1990s, then in Chechnya, in 1995. In a court filing unsealed in April this year, U.S. prosecutors called the files "a treasure-trove." Of special note was a handwritten list of names, topped by a verse from the Koran--"And spend for God's cause"--followed by 20 wealthy donors to the al Qaeda network, dating apparently from the late '80s. Known as the Golden Chain, the roster included some of Saudi Arabia's wealthiest men: three billionaire bankers, top industrialists, and a former government minister. After each man appeared a second name, in parenthesis, suggesting who received money from the donor. "Osama" appeared after seven entries.

America had taken bin Laden seriously only in 1998, after he destroyed two U.S. Embassies in Africa. But "Osama's History" showed unmistakably how the Saudi multimillionaire had declared war on the United States back in 1991, how for a decade he had branded America the "head of the snake" and rationalized the killing of American civilians. But perhaps the most striking find were the handwritten minutes of an Aug. 11, 1988, meeting. It was there that bin Laden and others agreed on "the establishment of a new military group" consisting of three units, one to be called, in Arabic, Qaeda, or Base. A week later at bin Laden's home, they held a second meeting--for three days--that led to the official founding of the new entity. "Work of al Qaeda commenced on 9/10/1988 with a group of 15 brothers . . ." concluded the report. "And thanks be to God."

Half-Dead Bob. By early 2002, America and its allies had locked up nearly 1,000 al Qaeda members and supporters. Planeloads of captives from Afghanistan soon filled the holding pens of Camp X-Ray, the hastily built prison at the U.S. naval base in Guantanamo Bay, Cuba. Some inmates left a lasting impression on their keepers, among them an emaciated fellow they called Half-Dead Bob.

The Arab fighter had come to Gitmo, as the base is called, weighing a bare 66 pounds last year. He had shrapnel wounds, suffered from tuberculosis, and had lost a lung. Army Maj. Gen. Michael Dunlavey vividly remembers his first encounter with "Bob." Dunlavey ran interrogations at the base until November of last year. By the time they met, Bob was making a rapid recovery. He had put on 50 pounds and, sitting across a table from Dunlavey, he thanked him for the food and medical treatment. "General, you are probably a good Christian," Dunlavey recalls him saying. "And you are probably a good man. But if I ever get free, I will kill you."

Dunlavey, a 57-year-old Army reservist and state trial judge in Erie, Pa., has rarely spoken publicly; his remarks come from a March speech at a Washington conference. Like many officials at Gitmo, Dunlavey came away alarmed by the interrogations. Like Half-Dead Bob, most appeared willing to die as martyrs. "These people are implacably committed to apocalyptic terrorism," Dunlavey concluded. "Their goal is the absolute destruction of America as we know it."

By last spring, Gitmo was filled with some 660 of Bob's fellow travelers. As a group, they reflect al Qaeda's extraordinary reach, hailing from no less than 42 countries (though nearly one fifth come from Saudi Arabia). From the start, the new prison was controversial, with human-rights groups raising questions about the detainees' legal status and treatment. Washington considers them not prisoners of war but "enemy combatants" subject to the military's justice system. They have been shackled, blindfolded, and forced to stand or kneel in the same position for hours. They have no access to attorneys. Moreover, the group has ranged in age from young teenagers to the elderly, and the intelligence value of many has been minimal. Criticism from U.S. allies prompted Secretary of State Colin Powell to write an April 14 letter to the Pentagon, arguing for release of some detainees.

While some may have been in the wrong place at the wrong time, officials close to the interrogations can tick off a series of high-profile cases in which the prisoners have proved useful. Gitmo detainees helped place "American Taliban" John Walker Lindh in an al Qaeda camp, for example, and gave tips that led to the breakup of alleged al Qaeda cells in Morocco and Lackawanna, N.Y.

Gitmo, though, is only one node in a network of holding centers and prisons the United States began using in the war on terrorism. There are a half-dozen others, all of them overseas and inaccessible to the press and the public. In Jordan, the CIA uses a special center at the country's remote al Jafr Prison, where it has shipped up to 100 al Qaeda suspects for initial interrogations (box, Page 22). In Afghanistan, the Pentagon and the CIA run major interrogation centers at bases in Bagram and Kandahar, where some 70 prisoners are still believed held. Another facility is at the joint British-American base on Diego Garcia. A tiny speck of real estate in the Indian Ocean, the island was once called "Gilligan's Island with guns" by Stars and Stripes, the military newspaper. U.S. interrogations, employing so-called stress-and-duress techniques, have also come under fire from human-rights groups. The tactics range from sensory overload--use of bright, 24-hour lighting and the playing of loud music--to sleep deprivation. But the most troubling questions are reserved for prisons run by friendly Muslim governments. The CIA has helped move dozens of detainees not only to Jordan but also to Egypt, Morocco, and even Syria. Dubbed "renditions," the transfers have stirred concern by critics over those nations' records for torture.

The Facilitator. The efforts of the Jordanians are especially valued by U.S. officials. Their interrogators are used not only at al Jafr but also at other U.S. detention centers. Asked if they have helped with questioning at Guantanamo, a Jordanian intelligence agent replied: "We did. We do. And we will do." Indeed, CIA officials say they prefer the Jordanians precisely because they do not torture (although human-rights reports note their nasty reputation for falaqa--beating prisoners on the soles of their feet). "It's not that we have better interrogators," the Jordanian agent explained. "But when you want to interrogate a fundamentalist, it is not easy to get into his mind when he considers you an infidel."

In the parlance of the intelligence world, such ties with friendly spy services are called liaison relationships. "The one thing the CIA does better than anybody is manage liaison relationships," says Milt Bearden, the agency's former chief of station in Pakistan. "We've done it for 50 years. Our job is to recruit the spirit and love by giving them stuff--and that gives us stuff."

"Giving them stuff," in fact, has been central to the CIA's war on al Qaeda. The idea is simple enough: After 9/11, the United States began, in effect, to contract out key portions of the war on terrorism. Millions of dollars in covert funding started flowing to friendly Muslim intelligence and security agencies. The top recipients: Egypt, Jordan, and Pakistan. Also on the list are Algeria, Morocco, and Yemen. Total payments have topped well over $20 million, intelligence sources say, an amount they consider a bargain. Washington, of course, has granted other incentives to key allies: training, equipment, debt forgiveness, economic assistance. U.S. aid to Pakistan ballooned from a paltry $5 million in 2001 to over $1.1 billion in 2002. Over the past year, aid to Jordan has more than quadrupled, to $1.6 billion.

"It is impossible to overestimate the importance that our Arab allies played--the Jordanians, the Egyptians, the North Africans," explains Roger Cressey, the former terrorism expert on the National Security Council. "They understand them better, they penetrated the cells--we certainly didn't."

The Pakistanis, however, draw the most praise. Pakistan served as midwife to the Taliban, helping bring the radical regime to power in neighboring Afghanistan. But after 9/11, Pakistani President Pervez Musharraf turned on a dime and cracked down on al Qaeda terrorists who sought refuge in his country. That policy netted the war on terror's biggest fish.

It began with Riyadh the Facilitator. Little is known about the man, whom Pakistani forces seized in Karachi in January 2002. Responsible for managing al Qaeda's affairs in Pakistan, he is one of a handful of important operatives about whom U.S. officials have released virtually no information. During the war, allied troops in Afghanistan nabbed a pair of middle managers, but Riyadh was the first field commander captured after 9/11. "Riyadh was a serious logistician," says an intelligence source. He was also the first link in a chain that would lead from one al Qaeda leader to another.

The tactics employed were basic enough. In newspaper ads, the Pakistani Army offered fat rewards for tips about strange foreigners. Riyadh's neighbors had noticed the odd comings and goings of people who entered his small home. Once in custody, he talked. Soon, investigators were chasing down leads into al Qaeda's growing presence in Pakistan.

The next jihadist domino to fall was much bigger. Abu Zubaydah was a rising star in al Qaeda. Just 31, the Saudi-born Palestinian already had served as the top recruiter for the group's training camps in Afghanistan. After its military chief, Mohammed Atef, died in the U.S. airstrike in Afghanistan, Zubaydah was tapped to replace him. He wasn't very good at it, investigators say. He set up shop in Pakistan's third-largest city, Faisalabad, but lasted only a month. The big break came, again, through a local tip.

Zubaydah's arrest took place just as U.S. analysts were digesting the windfall of intelligence from around the world. Interrogators now knew what questions to ask him. Even better, they knew some of the answers. "He initially gave us a bunch of outdated crap," says one official. But eventually he slipped up. He made reference to an American in the al Qaeda ranks, a tip that led weeks later to the Chicago arrest of alleged "dirty bomber" Jose Padilla, a former street hood who found his way to radical Islam. He identified a photo of Omar al Farouq, the Southeast Asia chief; two weeks later, authorities in Indonesia nabbed Farouq.

Turning point. The Pakistanis also recovered a trove of materials in Zubaydah's safe house--CDs, address books, financial records, a satellite phone. "It felt like the working documents of an organization," says a senior intelligence source. "Zubaydah's capture felt like a turning point." By the end of spring 2002, more than 100 CIA officers and FBI agents had poured into Pakistan, setting up units to work with local intelligence. The CIA brought eavesdropping devices; the FBI, forensic detective gear. The chase was on.

Next to fall was Ramzi Binalshibh, paymaster for the 9/11 hijackers. In September raids, the U.S.-Pakistani teams nabbed Binalshibh and others in Karachi. Along with their quarry they found three satellite phones, five laptop computers, wads of cash, and a small arsenal.

Weeks later, Moroccan prisoners at Gitmo began a chain reaction that struck another blow against al Qaeda. The detainees gave up details of an active cell in Morocco; within weeks, authorities busted the group, thwarting its plans to bomb U.S. and British warships in the Strait of Gibraltar. The Moroccan cell, in turn, led investigators to Abd al-Rahim al Nashiri, a top operative who ran al Qaeda's operations on the Saudi peninsula. In October, they found Nashiri, the mastermind of the USS Cole bombing, hiding in the United Arab Emirates, planning a series of naval strikes. Nashiri soon broke; he even let officials listen in as he called his associates. The result: A CIA Predator drone found the chief of his cell in Yemen, driving with four of his men on an isolated road. A Hellfire missile blasted apart their car, killing all.

Al Qaeda and its allies struck back in the fall of 2002. First came the October attack on a French oil tanker in Yemen. A week later: the Bali bombings, the worst single act of terrorism since 9/11, killing more than 200 people. Then on November 28, suicide bombers in Mombasa, Kenya, struck an Israeli-owned hotel, killing 16, while others nearly brought down an Israeli airliner with shoulder-fired missiles.

But the pressure on al Qaeda was unrelenting. "Almost half of our successes against senior al Qaeda members has come in recent months," declared CIA Director George Tenet in December. And in March of this year, a U.S.-Pakistani team racked up the biggest prize yet. When they picked up the trail of Khalid Shaikh Mohammed this spring, investigators thought they might have found the path to bin Laden himself. KSM, as he was called, had taken over as al Qaeda's chief of operations. Diabolically clever, he was known within al Qaeda as "the Brain" and is credited with masterminding the 9/11 attacks and a half-dozen other operations.

Mohammed, a 38-year-old Pakistani, was nabbed on March 1. "KSM," observed Cofer Black, "is like getting their chief of staff." Making the haul even better was KSM's companion: Mustafa Ahmed al-Hawsawi, an al Qaeda bagman who had wired cash to the 9/11 hijackers. With Hawsawi, agents found bank ledgers, the names of couriers and financiers, more phone numbers, and safe-house addresses. Investigators found an array of new suspects to track down, including more than a dozen sympathizers in America, Spain, and Switzerland. By spring of this year, the Pakistanis were arresting al Qaeda suspects almost weekly. The fight has been costly: Ten Pakistani soldiers lost their lives while raiding a safe house, and at least 10 others have been injured in the campaign. "We always say we captured these people, but that's not entirely true," says a U.S. official. "The first guy through the door is a Pakistani."

America's high-tech eavesdropping gear has given the hunters a crucial edge. "We've been using a lot of the tools that we couldn't use when al Qaeda was hiding in the mountains," explains former National Security Agency staffer Matthew Aid, an expert on electronic eavesdropping. Only in rare cases can homing gear give a satellite or cellphone's exact location, Aid says. What it can do, though, is pinpoint the receiver's neighborhoods, giving on-the-ground security forces a place to focus. And al Qaeda's troops have foolishly cooperated. Three of its top people--KSM, Zubaydah, and Binalshibh--all were caught with satellite phones.

Before 9/11, eavesdropping on al Qaeda was America's single best source of intelligence on the group. But the CIA had few human sources to take the next step. "We couldn't corroborate it; we couldn't act on it," says an intelligence official. That has changed. Also, al Qaeda operatives are not the high-tech terrorists some imagine. Their computer files are rarely encrypted, and when they are, U.S. officials have broken the codes easily. Nor have they used encrypted telephones. Al Qaeda's "codes" consist of simple word substitutes or use of flowery Arabic phrases. "They continue to make basic tradecraft mistakes," says Aid, "and one of them is you never talk over the phone." That message has reached the top: Bin Laden no longer uses the phone.

Bin Laden remains the world's most wanted man. He is thought to be hiding in the tribal badlands along Pakistan's northwest border. U.S. counterterrorism officials remain confident that they eventually will find him. "Ninety-six percent of what we operationally need is in place," says Black. "You're just waiting for the dime to drop."

Black left the CIA in late 2002. He now directs the State Department's Office of Counterterrorism. Like his old colleagues at the CIA, he remains wary, sobered by recent attacks in Saudi Arabia and Morocco. Al Qaeda, he says, remains a disturbingly lethal threat, with hundreds of operatives and would-be martyrs dispersed around the globe.

Al Qaeda 2.0. Borrowing a term from management theory, one counterterrorism veteran calls al Qaeda "a learning organization." It accumulates knowledge, develops new skills, and continually adapts to its environment. That, of course, is not good news. Peter Bergen, author of Holy War Inc., calls its latest incarnation al Qaeda 2.0, a more decentralized, more organic network of terrorism. The al Qaeda of 9/11--with its military training camps and millions of dollars--may in fact no longer exist, but in its place may be local cells that take on lives of their own. Instead of striving for catastrophic damage, they may concentrate on "soft" targets like the streets of Casablanca and the residences of Riyadh. And still, bin Laden's original creation may yet survive. Young jihadists could move into positions of leadership faster than America and its allies can track them down.

This much is clear: America waited too long to join the fray, and the battle is yet to be won. "I've never had a job where you can celebrate success, and you're still so paranoid at the end of the day," says a senior intelligence official. "I don't know if we'll ever be able to declare victory."

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